[cma-l] Radio Link Transmission systems

[Alan Coote]

Alex, 

Excellent information, very informative – thank you!

Ian, if you would like to know more (although Alex clearly knows his stuff), then I’m more than happy to put you in touch with the MD of a company who have vast experience setting these systems up.

Regards
 
Alan




From:  <cma-l-bounces at mailman.commedia.org.uk> on behalf of "tlr at gairloch.co.uk" <tlr at gairloch.co.uk>
Reply-To:  "cma-l at mailman.commedia.org.uk" <cma-l at mailman.commedia.org.uk>
Date:  Saturday, 4 June 2016 at 15:46
To:  "cma-l at mailman.commedia.org.uk" <cma-l at mailman.commedia.org.uk>
Subject:  [cma-l] [***SPAM***] Re:  Radio Link Transmission systems


Ah, I see, but he was just giving a broad description of the setup wasn't he?

Of course if you know the frequency (5.8GHz in this case), you can make a pretty good assumption about the antenna gain, pattern etc,  especially if it's a simple old single polarisation model. 

Alex
On 4 Jun 2016 14:08, Ian Hickling <transplanfm at hotmail.com> wrote:
All accepted Alex - yes - this is my subject as you know and has been for well over 50 years
I was simply pointing out to Alan that using the phrase "20cm patch antennas" in isolation conveys no useful information whatsoever.

Ian Hickling

Partner

Office: 016 3557 8435  (07h to 22h GTS)

Car: 075 3098 0115 (only responds when driving)

6 Horn Street, Compton, NEWBURY, RG20 6QS


From: tlr at gairloch.co.uk
To: cma-l at mailman.commedia.org.uk
Date: Sat, 4 Jun 2016 12:14:50 +0100
Subject: Re: [cma-l] Radio Link Transmission systems

Just look up the datasheets for any of the antennas Ian – they give all the usual polar patterns, gain figures, FB ratios etc as you would get for any broadcast antenna. They’re much what you expect – the panel antennas are in simplest terms just a broadside phased array, just like you might construct with conventional metalwork antennas.

 

As with the more familiar dipoles and Yagis they can be scaled and optimized for gain, pattern and operating frequencies, but typically aren’t used below 300MHz. Gains typically range over 0-24dBi, for higher gains dishes tend to be more practical and better controlled patterns. Panels tend to have more sidelobes and poorer front-back ratios than end fire arrays like Yagis or dishes, but can be relatively easily screened at higher frequencies.

 

Eg for the Jaybeam 14dB 568000 one we use on our STL: 

 

 

For a typical 5.8GHz 21dBi w-fi panel:

 

 

From: cma-l-bounces at mailman.commedia.org.uk [mailto:cma-l-bounces at mailman.commedia.org.uk] On Behalf Of Ian Hickling
Sent: 03 June 2016 22:45
To: The Community Media Association Discussion List <cma-l at mailman.commedia.org.uk>
Subject: [cma-l] Radio Link Transmission systems

 

I'm familiar with that general principle - very common in mobile phone base station panel construction - but as an antenna engineer I was more concerned with the operating frequency, forward gain and propagation pattern - which as yet are not clear from what I can read here.

Ian Hickling

Partner

Office: 016 3557 8435  (07h to 22h GTS)

Car: 075 3098 0115 (only responds when driving)

6 Horn Street, Compton, NEWBURY, RG20 6QS

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